320 research outputs found
Candidate Effectors From Uromyces appendiculatus, the Causal Agent of Rust on Common Bean, Can Be Discriminated Based on Suppression of Immune Responses
Rust fungi are devastating pathogens for several important crop plants. The biotrophic lifestyle of rust fungi requires that they influence their host plants to create a favorable environment for growth and reproduction. Rust fungi secrete a variety of effector proteins that manipulate host target proteins to alter plant metabolism and suppress defense responses. Because of the obligate biotrophic lifestyle of rust fungi, direct evidence for effector function is difficult to obtain, and so suites of experiments utilizing expression in heterologous systems are necessary. Here, we present results from a yeast cell death suppression assay and assays for suppression of PAMP-triggered immunity (PTI) and effector triggered immunity (ETI) based on delivery of effectors through the bacterial type III secretion system. In addition, subcellular localization was tested using transient expression of GFP fusion proteins in Nicotiana benthamiana through Agrobacterium infiltration. We tested 31 representative effector candidates from the devastating common bean rust pathogen Uromyces appendiculatus. These effector candidates were selected based on features of their gene families, most important lineage specificity. We show that several of our effector candidates suppress plant defense. Some of them also belong to families of effector candidates that are present in multiple rust species where their homologs probably also have effector functions. In our analysis of candidate effector mRNA expression, some of those effector candidates that gave positive results in the other assays were not up-regulated during plant infection, indicating that either these proteins have functions at multiple life stages or that strong up-regulation of RNA level in planta may not be as important a criterion for identifying effectors as previously thought. Overall, our pipeline for selecting effector candidates based on sequence features followed by screening assays using heterologous expression systems was successful in discriminating effector candidates. This work lays the foundation for functional characterization of U. appendiculatus effectors, the identification of effector targets, and identification of novel sources for resistance in common bean
Chaperoning to the metabolic party:the emerging therapeutic role of heat-shock proteins in obesity and type 2 diabetes
Background: From their initial, accidental discovery 50 years ago, the highly conserved Heat Shock Proteins (HSPs) continue to exhibit fundamental roles in the protection of cell integrity. Meanwhile, in the midst of an obesity epidemic, research demonstrates a key involvement of low grade inflammation, and mitochondrial dysfunction amongst other mechanisms, in the pathology of insulin resistance and type 2 diabetes mellitus (T2DM). In particular, tumor necrosis factor alpha (TNFα), endoplasmic reticulum (ER) and oxidative stress all appear to be associated with obesity and stimulate inflammatory kinases such as c jun amino terminal kinase (JNK), inhibitor of NF-ÎșÎČ kinase (IKK) and protein kinase C (PKC) which in turn, inhibit insulin signaling. Mitochondrial dysfunction in skeletal muscle has also been proposed to be prominent in the pathogenesis of T2DM either by reducing the ability to oxidize fatty acids, leading to the accumulation of deleterious lipid species in peripheral tissues such as skeletal muscle and liver, or by altering the cellular redox state. Since HSPs act as molecular chaperones and demonstrate crucial protective functions in stressed cells, we and others have postulated that the manipulation of HSP expression in metabolically relevant tissues represents a therapeutic avenue for obesity-induced insulin resistance.
Scope of Review: This review summarizes the literature from both animal and human studies, that has examined how HSPs, particularly the inducible HSP, Heat Shock Protein 72 (Hsp72) alters glucose homeostasis and the possible approaches to modulating Hsp72 expression. A summation of the role of chemical chaperones in metabolic disorders is also included.
Major Conclusions: Targeted manipulation of Hsp72 or use of chemical chaperiones may have clinical utility in treating metabolic disorders such as insulin resistance and T2DM
Surface Laplacian of Central Scalp Electrical Signals is Insensitive to Muscle Contamination
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any copyrighted components of this work in other works."AbstractâObjective: To investigate the effects of surface
Laplacian processing on gross and persistent electromyographic
(EMG) contamination of electroencephalographic (EEG) signals
in electrical scalp recordings.
Methods: We made scalp recordings during passive and active
tasks, on awake subjects in the absence and in the presence of
complete neuromuscular blockade. Three scalp surface
Laplacian estimators were compared to left ear and common
average reference (CAR). Contamination was quantified by
comparing power after paralysis (brain signal, B) with power
before paralysis (brain plus muscle signal, B+M). Brain:Muscle
(B:M) ratios for the methods were calculated using B and
differences in power after paralysis to represent muscle (M).
Results: There were very small power differences after
paralysis up to 600 Hz using surface Laplacian transforms (B:M>
6 above 30 Hz in central scalp leads).
Conclusions: Scalp surface Laplacian transforms reduce
muscle power in central and peri-central leads to less than one
sixth of the brain signal, 2-3 times better signal detection than
CAR.
Significance: Scalp surface Laplacian transformations provide
robust estimates for detecting high frequency (gamma) activity,
for assessing electrophysiological correlates of disease, and also
for providing a measure of brain electrical activity for use as a
âstandardâ in the development of brain/muscle signal separation
methods
Analytical Investigation of Innovation Dynamics Considering Stochasticity in the Evaluation of Fitness
We investigate a selection-mutation model for the dynamics of technological
innovation,a special case of reaction-diffusion equations. Although mutations
are assumed to increase the variety of technologies, not their average success
("fitness"), they are an essential prerequisite for innovation. Together with a
selection of above-average technologies due to imitation behavior, they are the
"driving force" for the continuous increase in fitness. We will give analytical
solutions for the probability distribution of technologies for special cases
and in the limit of large times.
The selection dynamics is modelled by a "proportional imitation" of better
technologies. However, the assessment of a technology's fitness may be
imperfect and, therefore, vary stochastically. We will derive conditions, under
which wrong assessment of fitness can accelerate the innovation dynamics, as it
has been found in some surprising numerical investigations.Comment: For related work see http://www.helbing.or
Characterization of Soybean STAY-GREEN Genes in Susceptibility to Foliar Chlorosis of Sudden Death Syndrome
Fusarium virguliforme causes sudden death syndrome (SDS) of soybean (Glycine max) in the United States. This fungal pathogen inhabits soil and produces multiple phytotoxins, which are translocated from infected roots to leaves, causing SDS foliar chlorosis and necrosis (Hartman et al., 2015). Because SDS foliar symptoms are solely induced by phytotoxins, it represents a unique pathosystem to study plant-phytotoxin interactions (Chang et al., 2016). SDS foliar symptoms typically appear near flowering through late reproductive growth stages, with chlorotic spots that gradually develop into interveinal chlorosis and necrosis (Fig. 1A). The sudden appearance of SDS foliar symptoms not only explains the origin of the disease name, but also reflects the difficulty of early detection in managing this disease. Yield reductions caused by SDS have been documented at 5% to15%, and the economic loss was estimated up to $669 million U.S. dollars in a single year (Navi and Yang, 2016). Seed treatments have been used to manage SDS, but performance differs by year and location. Alternatively, partially resistant soybean cultivars provide a sustainable option for SDS management, but the genetic architecture of SDS resistance is quantitative and complicated. Among more than 80 quantitative trait loci reported for SDS, only a few quantitative trait loci are reproducible due to the complexity of SDS etiology and environmental interactions (Chang et al., 2018)
Nextâgeneration sequencing reveals that miRâ16â5p, miRâ19aâ3p, miRâ451a, and miRâ25â3p cargo in plasma extracellular vesicles differentiates sedentary young males from athletes
A sedentary lifestyle and Olympic participation are contrary risk factors for global mortality and incidence of cancer and cardiovascular disease. Extracellular vesicle miRNAs have been described to respond to exercise. No molecular characterization of young male sedentary people versus athletes is available; so, our aim was to identify the extracellular vesicle miRNA profile of chronically trained young endurance and resistance male athletes compared to their sedentary counterparts. A descriptive caseâcontrol design was used with 16 sedentary young men, 16 Olympic male endurance athletes, and 16 Olympic male resistance athletes. Nextâgeneration sequencing and RTâqPCR and external and internal validation were performed in order to analyze extracellular vesicle miRNA profiles. Endurance and resistance athletes had significant lower levels of miRâ16â5p, miRâ19aâ3p, and miRâ451a compared to sedentary people. Taking all together, exerciseâtrained miRNA profile in extracellular vesicles provides a differential signature of athletes irrespective of the type of exercise compared to sedentary people. Besides, miRâ25â3p levels were specifically lower in endurance athletes which defines its role as a specific responder in this type of athletes. In silico analysis of this profile suggests a role in adaptive energy metabolism in this context that needs to be experimentally validated. Therefore, this study provides for the first time basal levels of circulating miRNA in extracellular vesicles emerge as relevant players in intertissue communication in response to chronic exercise exposure in young elite male athletes
Three-phase traffic theory and two-phase models with a fundamental diagram in the light of empirical stylized facts
Despite the availability of large empirical data sets and the long history of
traffic modeling, the theory of traffic congestion on freeways is still highly
controversial. In this contribution, we compare Kerner's three-phase traffic
theory with the phase diagram approach for traffic models with a fundamental
diagram. We discuss the inconsistent use of the term "traffic phase" and show
that patterns demanded by three-phase traffic theory can be reproduced with
simple two-phase models, if the model parameters are suitably specified and
factors characteristic for real traffic flows are considered, such as effects
of noise or heterogeneity or the actual freeway design (e.g. combinations of
off- and on-ramps). Conversely, we demonstrate that models created to reproduce
three-phase traffic theory create similar spatiotemporal traffic states and
associated phase diagrams, no matter whether the parameters imply a fundamental
diagram in equilibrium or non-unique flow- density relationships. In
conclusion, there are different ways of reproducing the empirical stylized
facts of spatiotemporal congestion patterns summarized in this contribution,
and it appears possible to overcome the controversy by a more precise
definition of the scientific terms and a more careful comparison of models and
data, considering effects of the measurement process and the right level of
detail in the traffic model used.Comment: 18 pages in the published article, 13 figures, 2 table
Solitons and diffusive modes in the noiseless Burgers equation: Stability analysis
The noiseless Burgers equation in one spatial dimension is analyzed from the
point of view of a diffusive evolution equation in terms of nonlinear soliton
modes and linear diffusive modes. The transient evolution of the profile is
interpreted as a gas of right hand solitons connected by ramp solutions with
superposed linear diffusive modes. This picture is supported by a linear
stability analysis of the soliton mode. The spectrum and phase shift of the
diffusive modes are determined. In the presence of the soliton the diffusive
modes develop a gap in the spectrum and are phase-shifted in accordance with
Levinson's theorem. The spectrum also exhibits a zero-frequency translation or
Goldstone mode associated with the broken translational symmetry.Comment: 9 pages, Revtex file, 5 figures, to be submitted to Phys. Rev.
Exercise training improves long-term memory in obese mice
Obesity has been linked to a range of pathologies, including dementia. In contrast, regular physical activity is associated with the prevention or reduced progression of neurodegeneration. Specifically, physical activity can improve memory and spatial cognition, reduce age-related cognitive decline, and preserve brain volume, but the mechanisms are not fully understood. Accordingly, we investigated whether any detrimental effects of high-fat diet (HFD)-induced obesity on cognition, motor behavior, adult hippocampal neurogenesis, and brain-derived neurotrophic factor (BDNF) could be mitigated by voluntary exercise training in male C57Bl/6 mice. HFD-induced impairment of motor function was not reversed by exercise. Importantly, voluntary wheel running improved long-term memory and increased hippocampal neurogenesis, suggesting that regular physical activity may prevent cognitive decline in obesity
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